In commonly used authentication methods, it is required to input a password, biometric authentication information, or the like. Among the authentication methods, there are methods of performing authentication in two steps by using two terminals (a first terminal and a second terminal), and in both the steps, it is required to input a password, biometric authentication information, or the like. For example, in an authentication method described in Patent document 1 cited below, it is required to first input an ID and a password on a PC ([0019]), and next input biometric authentication information, such as voice, a face, or a finger print, of a user from an information mobile terminal. The input of the password, the biometric authentication information, and the like is a burden for the user and is time-consuming. Therefore, the inventors proposed an authentication system that does not require input of knowledge authentication information except for authentication information such as a user ID and a card ID, belongings authentication information, and biometric authentication information during authentication (see Patent Literature 2 described below).